Transcription profiling of yeast double aft1aft2 deletion mutant in growth assays

ABSTRACT: Iron homeostasis in the yeast Saccharomyces cerevisiae is regulated at the transcriptional level by Aft1p, which activates the expression of its target genes in response to low-iron conditions. The yeast genome contains a paralog of AFT1, which has been designated AFT2. To establish whether AFT1 and AFT2 have overlapping functions, a mutant containing a double aft1aft2 deletion was generated. Growth assays established that the single aft2 strain exhibited no iron-dependent phenotype. However, the double-mutant aft1aft2 strain was more sensitive to low-iron growth conditions than the single-mutant aft1 strain. A mutant allele of AFT2 (AFT2-1up), or overexpression of the wild-type AFT2 gene, led to partial complementation of the respiratory- deficient phenotype of the aft1 strain. The AFT2-1up allele also increased the uptake of 59Fe in an aft1 strain. DNA microarrays were used to identify genes regulated by AFT2. Some of the AFT2-regulated genes are known to be regulated by Aft1p; however, AFT2-1up-dependent activation was independent of Aft1p. The kinetics of induction of two genes activated by the AFT2-1up allele are consistent with Aft2p acting as a direct transcriptional factor. Truncated forms of Aft1p and Aft2p bound to a DNA duplex containing the Aft1p binding site in vitro. The wild-type allele of AFT2 activated transcription in response to growth under low-iron conditions. Together, these data suggest that yeast has a second regulatory pathway for the iron regulon, with AFT1 and AFT2 playing partially redundant roles.

ORGANISM(S): Saccharomyces cerevisiae

SUBMITTER: Esha Ray 

PROVIDER: E-SMDB-1517 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress